guitar effects demo (plus some code)

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I've ported a bunch of my effects to a $50 ARM 7 eval board from ST Micro.

https://www.youtube.com/watch?v=OoRuUit7FyM

I spent quite a bit of time working on the distortion. It's much less trivial than I'd imagined to do nice sounding distortion.

Here's a link to C code for my piece-wise linear approximation distortion effect:

http://denniscronin.net/dsp/distortion-sample.c

I used another tool to generate the piece-wise values and then the distortion effect takes the selected curve and generates the linear interpolation for each input value. Thus I can switch distortion curves easily.

The distortion effect also has rudimentary slew rate limiting (audible result is a low pass sort of thing) and sag which at higher values yields pretty awful sounding distortion like a tube amp with a failing power supply.

You need to pre-eq things appropriately like the tone stack on a real amp, and then maybe throw a little cabinet filtering on the back end.

Enjoy.

CAF

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Did you actually file a patent for any of this? :?

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A patent? For code ported from PC/macOS/... to an embedded platform??
Anyway, this is not acceptable according to Alice vs I don't remember who. Just having something on a computer doesn't make a patent.

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Thanks foil. Looks like fun. Your code uses floats. Does your $50 dev board have a hardware vfp float processor unit, or is your float math via soft math library?

I'm totally ignorant of Arms. Only googled it long enough to read that arm7 can be had either with or without hardware float math. I don't even know whether hardware float math would be faster than float via integer float lib routines, on that kind of processor. So maybe hardware float math wouldn't even matter much? Dunno.

It do look like inexpensive fun.

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With NEON, it works really well. Not sure if the ST Micro version has them...

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Miles1981 wrote:A patent? For code ported from PC/macOS/... to an embedded platform??
Anyway, this is not acceptable according to Alice vs I don't remember who. Just having something on a computer doesn't make a patent.
Watch the video, I guess the patent is about the adaptive guitar fx. Seems pretty cool to me!

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Sorry, but I don't see the patent. It's just simple math on a computer.

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Back in 90's when the Line6 patent (the one about the use of oversampling to reduce aliasing) had became known , I wasn't able to see why it was granted either, it seemed like obvious math.

Mesa Boogie has many patents that seem obvious. Have a look at these and think if you would grant a patent for all of them
http://www.mesaboogie.com/support/patents.html

Software patents in general are even more ridiculous. The way items are displayed in an iPhone menu can be a subject matter for a patent (I don't have a reference now, but I have seen that something like this was actually patented).

Seems like it's more about the capability of your lawyer than the patented content itself.
~stratum~

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Miles1981 wrote:Sorry, but I don't see the patent. It's just simple math on a computer.
Patents don't require the invention to be particularly complex. And it's also not forbidden to *implement* the invention using computer hardware. A term that often comes up in patent texts is an "embodiment".

Patents are even more useful if the idea and implementation is very simple. If it's hard enough to do, you don't need a patent to prevent others from copying it. In fact, you might not want to be forced to publish details about your invention if it's not obvious for a skillful competitor to figure out.

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Well, I don't see what's new here. It depends on the level of the input? That exists for years.
And I don't agree. Patenting something easy is bad because it usually exists already and it's a pain to fight because of the USPO being so...

I don't have an issue on the port on ARM, that's nice. I have a problem with patenting it. Just as I won't patent a new triode model.

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